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Commit9dc718b

Browse files
Pass down "logically unchanged index" hint.
Add an executor aminsert() hint mechanism that informs index AMs thatthe incoming index tuple (the tuple that accompanies the hint) is notbeing inserted by execution of an SQL statement that logically modifiesany of the index's key columns.The hint is received by indexes when an UPDATE takes place that does notapply an optimization like heapam's HOT (though only for indexes whereall key columns are logically unchanged). Any index tuple that receivesthe hint on insert is expected to be a duplicate of at least oneexisting older version that is needed for the same logical row. Relatedversions will typically be stored on the same index page, at leastwithin index AMs that apply the hint.Recognizing the difference between MVCC version churn duplicates andtrue logical row duplicates at the index AM level can help with cleanupof garbage index tuples. Cleanup can intelligently target tuples thatare likely to be garbage, without wasting too many cycles on lesspromising tuples/pages (index pages with little or no version churn).This is infrastructure for an upcoming commit that will teach nbtree toperform bottom-up index deletion. No index AM actually applies the hintjust yet.Author: Peter Geoghegan <pg@bowt.ie>Reviewed-By: Victor Yegorov <vyegorov@gmail.com>Discussion:https://postgr.es/m/CAH2-Wz=CEKFa74EScx_hFVshCOn6AA5T-ajFASTdzipdkLTNQQ@mail.gmail.com
1 parent39b0369 commit9dc718b

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31 files changed

+214
-25
lines changed

31 files changed

+214
-25
lines changed

‎contrib/bloom/blinsert.c‎

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@@ -198,6 +198,7 @@ bool
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blinsert(Relationindex,Datum*values,bool*isnull,
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ItemPointerht_ctid,RelationheapRel,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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IndexInfo*indexInfo)
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{
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BloomStateblstate;

‎contrib/bloom/bloom.h‎

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@@ -192,6 +192,7 @@ extern bool blvalidate(Oid opclassoid);
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externboolblinsert(Relationindex,Datum*values,bool*isnull,
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ItemPointerht_ctid,RelationheapRel,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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structIndexInfo*indexInfo);
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externIndexScanDescblbeginscan(Relationr,intnkeys,intnorderbys);
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externint64blgetbitmap(IndexScanDescscan,TIDBitmap*tbm);

‎doc/src/sgml/indexam.sgml‎

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@@ -293,6 +293,7 @@ aminsert (Relation indexRelation,
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ItemPointer heap_tid,
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Relation heapRelation,
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IndexUniqueCheck checkUnique,
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bool indexUnchanged,
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IndexInfo *indexInfo);
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</programlisting>
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Insert a new tuple into an existing index. The <literal>values</literal> and
@@ -308,6 +309,20 @@ aminsert (Relation indexRelation,
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look into the heap to verify tuple liveness).
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</para>
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<para>
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The <literal>indexUnchanged</literal> boolean value gives a hint
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about the nature of the tuple to be indexed. When it is true,
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the tuple is a duplicate of some existing tuple in the index. The
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new tuple is a logically unchanged successor MVCC tuple version. This
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happens when an <command>UPDATE</command> takes place that does not
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modify any columns covered by the index, but nevertheless requires a
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new version in the index. The index AM may use this hint to decide
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to apply bottom-up index deletion in parts of the index where many
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versions of the same logical row accumulate. Note that updating a
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non-key column does not affect the value of
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<literal>indexUnchanged</literal>.
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</para>
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<para>
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The function's Boolean result value is significant only when
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<literal>checkUnique</literal> is <literal>UNIQUE_CHECK_PARTIAL</literal>.

‎src/backend/access/brin/brin.c‎

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@@ -151,6 +151,7 @@ bool
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brininsert(RelationidxRel,Datum*values,bool*nulls,
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ItemPointerheaptid,RelationheapRel,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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IndexInfo*indexInfo)
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{
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BlockNumberpagesPerRange;

‎src/backend/access/common/toast_internals.c‎

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@@ -328,7 +328,7 @@ toast_save_datum(Relation rel, Datum value,
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toastrel,
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toastidxs[i]->rd_index->indisunique ?
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UNIQUE_CHECK_YES :UNIQUE_CHECK_NO,
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NULL);
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false,NULL);
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}
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/*

‎src/backend/access/gin/gininsert.c‎

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@@ -488,6 +488,7 @@ bool
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gininsert(Relationindex,Datum*values,bool*isnull,
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ItemPointerht_ctid,RelationheapRel,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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IndexInfo*indexInfo)
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{
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GinState*ginstate= (GinState*)indexInfo->ii_AmCache;

‎src/backend/access/gist/gist.c‎

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@@ -156,6 +156,7 @@ bool
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gistinsert(Relationr,Datum*values,bool*isnull,
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ItemPointerht_ctid,RelationheapRel,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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IndexInfo*indexInfo)
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{
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GISTSTATE*giststate= (GISTSTATE*)indexInfo->ii_AmCache;

‎src/backend/access/hash/hash.c‎

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@@ -247,6 +247,7 @@ bool
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hashinsert(Relationrel,Datum*values,bool*isnull,
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ItemPointerht_ctid,RelationheapRel,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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IndexInfo*indexInfo)
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{
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Datumindex_values[1];

‎src/backend/access/heap/heapam_handler.c‎

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@@ -1956,6 +1956,7 @@ heapam_index_validate_scan(Relation heapRelation,
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heapRelation,
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indexInfo->ii_Unique ?
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UNIQUE_CHECK_YES :UNIQUE_CHECK_NO,
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false,
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indexInfo);
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state->tups_inserted+=1;

‎src/backend/access/index/indexam.c‎

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@@ -179,6 +179,7 @@ index_insert(Relation indexRelation,
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ItemPointerheap_t_ctid,
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RelationheapRelation,
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IndexUniqueCheckcheckUnique,
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boolindexUnchanged,
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IndexInfo*indexInfo)
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{
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RELATION_CHECKS;
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returnindexRelation->rd_indam->aminsert(indexRelation,values,isnull,
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heap_t_ctid,heapRelation,
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checkUnique,indexInfo);
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checkUnique,indexUnchanged,
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indexInfo);
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}
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/*

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